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Police radio and other types of two-way radio often use simulcast to increase range. Frequency control is crucial in these systems. In the past, frequency control was accomplished by using matched quartz oscillators. This ensured that the oscillators at all sites were very close in frequency, but it also required calibration at each transmit site once or twice a year for low- and high-band systems. Re-calibration at UHF and 800 MHz systems needed to occur much more frequently. Maintaining and calibrating oscillators on a regular basis could be very costly.
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Most frequency control methods today reference the Global Positioning System (ÃÛÌÒÊÓƵ). This method requires no re-calibration and the frequency accuracy is better than 0.01 hertz at the carrier frequency. ÃÛÌÒÊÓƵ offers several helpful products to minimize costs when upgrading a simulcast system.

One such product is the Tycho II Precision TimeBase. The Tycho II is a very reliable time and frequency standard with an MTBF of over 30 years.ÌýIn addition to a 1 PPS output, Tycho II's modular architecture supports up to twenty 10 MHz frequency output signals with exceptional spectral purity and high channel-to-channel signal isolation. Features include:

• A 1 PPS output better than 25Ìýnanoseconds RMS toÌýUTC(USNO).
• A frequency accuracy better than 6x10-14 at one day.
• Up to twenty 10 MHz low-phase-noise outputs.
• An alarm output
• Dual network ports with NTP, SSH, TELNET, FTP, and more.
• An RS-232 serial port.
• Two-year warranty, free technical support and software upgrades for life.
• Options: Dual redundant power supplies (AC and DC), 10 MPPS, pulse rates and more.